Corrosion inhibited composition



taining small amounts of moisture.

htates atent ice Patented Mar. 6, 1962 3,024,259 CORRQSI DN INHIBITEDCOMPOSITIGN David D. Sheldahl, Grifiith, Ind., and Thomas 0. Counts,

Park Forest, 111., assignors to Sinclair Refining Company, New York,N.Y., a corporation of Maine N Drawing. Original application July 30,1957, Ser- No. 675,016. Divided and this application Sept. 1, 1960, Ser.No. 56,620

3 Claims. (Cl. 26tl-4tll) This invention relates to new compositions ofmatter and more particularly to a new class of chemical compoundsderived from the reaction of a monocarboxylic acid, a fatty amidodiamine and an aromatic sulfonic acid. In other aspects this inventionrelates to novel compositions of matter and their use as a corrosioninhibitor in liquid mineral oils which normally come in contact withmetals.

Various corrosion inhibitors have been suggested for use in liquidmineral oil bases for the protection of metal surfaces, both internaland external, which come in contact with the base oils. Many of theseinhibitors when included in distillate fuels, for example, have proveddisadvantageous inasmuch as films produced therefrom do not exhibitsufficient resistance to moisture, particularly under high humidityconditions. In many applications, as in diesel engine flushing fuels,for example, the base oil must be inhibited against corrosion under highhumidity conditions and at the same time it is desirable, and in factsome specifications require, that the inhibitor be ashless.

In accordance with this invention We have found that corrosion problemsoccurring from mineral oils contacting metallic surfaces can bematerially lessened through use of novel corrosion inhibitors preparedby reacting cer tain fatty amido diamines, monocarboxylic acids andaromatic sulfonic acids. The inhibitor products are identified asmono-sulfonate fatty amido diamine salts of monocarboxylic acids and asshown hereinafter, these reaction products have been found to exhibitmarked protection of metal surfaces, particularly ferrous surfaces,which are in contact with liquid mineral oil products con- When blendedin mineral oil products such as gasoline and diesel fuel, such fuelseasily pass humidity cabinet corrosion tests which thus indicates theirresistance to moisture under high humidity conditions. Moreover, theinhibitors give protection in static and dynamic systems, e.g. storagetanks and pipelines. The novel inhibitor products of this inventioneffectively prevent corrosition without influencing basiccharacteristics of the mineral oil products in which they areincorporated and are further advantageous in that they will not form acombustion ash upon being subjected to relatively high temperatures.

The corrosion inhibiting compositions of this invention are formed byadding to a suitable mineral oil base a compound or mixture of compoundshaving the formula:

in which R and R represent monovalent hydrocarbon radicals containingfrom about 6 to 22 carbon atoms, R is the aromatic hydrocarbon radicalderived from aromatic sulfonic acids, and R and R are divalent aliphatichydrocarbon radicals, each of about 2 to 8 carbon atoms, branched orstraight chained and substituted or unsubstituted. The groups R and Rmay be alike or different, saturated or unsaturated, straight chain orbranched chain, may contain substituent groups such as amino, halogen,hydroxy, nitrile, and the like and preferably are aliphatic.

The novel corrosion inhibiting compounds of the present invention arethe mineral oilcompatible, i.e. dispersible, solubleor miscible Withoutcontinuing agitation, materials identified as mono-sulfonate fatty amidodiamine salts of monocarboxylic acids and can be prepared, for example,by reacting an aromatic sulfonic acid and monocarboxylic acid instoichiometric amounts with the fatty amido diamine. The reaction isalmost instantaneous if carried out at a temperature between about to F.but will occur slowly at room temperature. If desired, the reaction maybe effected with the aid of a solvent or at higher temperatures belowthe decomposition point of the reactants or product, Advantageously, asshown hereinafter, more than the stoichiometric amounts of the reactantscan be employed; for example, up to twice as much or more of thereactants can be present and the excess resulting from the reaction maybe included with the principal corrosion inhibiting salt when added to amineral oil base.

The fatty amido diamines which are used in accordance with the inventionare represented by the following general formula:

in which R is a hydrocarbon group containing at least about 6 andpreferably 12 to 22 carbon atoms and R and R are as described above.Preferably, R and R are polymethylene groups of about 2 to 8 carbonatoms, advantageously 2 to 4 carbon atoms. The members of this class ofdiamine compounds are cationic and possess one primary and secondaryamine group in addition to an acyl radical attached to the amidenitrogen. The acyl radical in the above formula may be straight orbranched chain, or alicyclic, may contain substituent groups such ashalogen, amino, hydroxy, nitrile, and the like, and is preferably analiphatic carboxylic acid residue of high molecular weight fatty acids,either saturated or unsaturated. Examples of such acids are oleic acid,stearic acid, palmitic acid, linoleic acid, linolenic acid, recinoleicacid, monohydroxy stearic acid, lauric acid, high molecular weightnaphthenic acids, fatty acids obtained from the oxidation of petroleumWaxes, and the like. Fatty acids which are particularly desirable forproviding the carboxylic acid residue can be obtained from vegetableoils and animal fats such as soybean oil, coconut oil, lard oil, cornoil, castor oil, tallow, and the like. Other suitable carboxylic acidresidues having the desired number of carbon atoms are the acidsobtained from tall oil which contains a mixture of fatty acids and resinacids.

The fatty amido diamines can be prepared by reacting a polyalkylenetriamine of the formula in which n is a number from about 2 to 8,preferably 2 to 4, with a carboxylic acid or a derivative thereof, suchas an ester, anhydride, or halide in such proportions and under suchconditions as to effect monoacylation of one primary amino group presentin the polyalkylene triamine. Fatty glycerides are examples of estersthat are good acylating agents, and particularly preferred materials arecorn oil or tallow which provide a saturated and unsaturated aliphatichydrocarbon group of from about 16 to 18 carbon atoms. The fatty amidodiamine is prepared by reacting a ratio of 1 mole of fatty acid for eachmole of polyalkylene triamine at a temperature above 250 F. andpreferably at a temperature of about 300 to 350 F. At temperatures belowabout 250 F., the reaction products will consist of salts of thepolyalkylene triarnine rather than the amide. Other methods ofpreparation which are satisfactory include reaction of the desired fattyacid and polyalkylene triamine with ammonia to obtain the correspondingamide. The amide is then reacted twice with acrylonitrile with eachreaction being followed by hydrogenation to produce the final fattyamido diamine product.

An example of a preferred fatty amido diamine used in the preparation ofthe corrosion inhibitors of this invention is a commercial productdesignated as Diamine 257 which corresponds to the above fatty amidodiamine formula in which R and R are trimethylene and R is the straightchain unsaturated hydrocarbon radical derived from corn oil and havingabout 16 to 18 carbon atoms. This product is well known, being marketedby Leyda Oil and Chemical Works, and is characterized by having an acidnumber of less than 5, an average amine equivalent Weight of 210, andone primary and secondary basic amine group. The product has anappearance of a viscous liquid or fluid paste and has a density of 0.935at 25 C.

The monocarboxylic acids which are used in the pressent invention arehigh molecular organic monocarboxylic acids of the formula R'--COOH inwhich R represents a hydrocarbon residue or radical containing about 6to 22 carbon atoms. The monocarboxylic acids may be straight chain orbranched chain, substituted or unsubstituted, saturated or unsaturated,and include such acids as capric acid, caproic acid, undecylic acid,lauric acid, myristic acid, ricinoleic, oleic acid, linoleic, stearicacid, palmitic acid, margaric acid, arachidic acid, mixtures of any twoor more of these acids or others, fatty acids derived from animal orvegetable sources, hydroxy and alpha-hydroxy fatty acids such as hydroxystearic acid, dihydroxy stearic acid, alpha-hydroxy stearic acid,alpha-hydroxy lauric acid, and fatty acids derived from various waxessuch as beeswax, spermaceti, and the like. Similarly, we may usemonocarboxylic acids derived by oxidation of petroleum waxes, such asslack wax, crude foots oil, microcrystalline wax, etc., as well asnaphthenic acid and abietic acid. Although reaction products formed fromthe various above carboxylic acids are effective corrosion inhibitors,the preferred monocarboxylic acids used in accordance with thisinvention are those in which the hydrocarbon radical contains from about12 to 18 carbon atoms, saturated or unsaturated, such as stearic acid,linoleic acid and palmitic acid, with particular preference beingdirected to oleic acid.

The sulfonic acid materials which can be used in the preparation of thecorrosion inhibitors of this invention are the aromatic sulfonic acidsincluding those derived from petroleum products. The useful petroleumsulfonic acids thus include the water-soluble or water-dispersible greenacids and the preferentially oil-soluble acids referred to as mahoganyacids. The green acids are found in the acid sludge resulting from thetreatment of a suitable petroleum oil such as a liquid petroleumdistillate boiling in the range, of 600 to 1000 F. with fuming sulfuricacid or sulfur trioxide, and are in fact mixtures of water-solublesulfonic acids known as black acids, intermediate detergent-typesulfonic acids, and oil-soluble sulfonic acids called brown acids. Thegreen acids are hydrophilic in character and can be recovered from theacid sludge by adding water to the sludge to dilute the sulfuric acidtherein to a concentration of about 20 to 30 percent, at whichconcentration the green acids separate to form the supernatant layer, orthey can be extracted from the sludge by using water-soluble solvents.

The

mahogany acids, some of which show limited hydrophilic properties, areoil-soluble or hydrophobic by nature and can be recovered from the acidtreated oil or obtained as a concentrate in the acid oil varying from 10to 50 percent by weight. The useful mahogany acids generally have amolecular weight of from about 300 to 500, or more, and although theirexact chemical structures may vary, it appears that such acids arecomposed to a large extent of sulfonated aro'rnatic hydrocarbons havingeither one or two aromatic rings per molecule possibly with one or morelong-chain alkyl groups containing from about 8 to 30 carbon atomsattached to the ring nuclei.

Suitable sulfonic acids which include both the oil and water-solublepetroleum sulfonic acids are the aryl sulfonic acids, benzene sulfonicacids, cymene sulfonic acid, naphthalene, sulfonic acid, alkylatednaphthalene sulfonic acid, fatty sulfonic and fatty aromatic sulfonicacids. Other useful aromatic sulfonic acids are the oil-soluble ammonianeutralized sulfonated mixtures of polyalkylated benzenes; alkyl arylsulfonic acids in which the alkyl chain contains from about 8 to 18carbon atoms; synthetic sulfonic acids prepared by reaction of paraffinwax chains of 20 or more carbons with aromatic nuclei which are thensulfonated by fuming sulfuric acid, e.g. wax substituted naphthalene;ammonium mahogany sulfonic acids obtained by reaction of ammonia withsulfuric acid treated hydrocarbon oils, ammonium sulfonates of the alkylaryl sulfonic acids, particularly those having a monocyclic nucleus, allof which are available or may be readily prepared by known methods.Particularly suitable sulfonic acid materials are ammonia neutralizedsulfonated Neolene bottoms described in US. Patent No. 2,671,757 to T.G. Wisherd, and the ammonium mahogany sulfonates described in U.S.Patent No. 2,632,694 to F. M. Watkins. The aromatic oil-soluble sulfonicacids are conveniently employed as a concentrate in the oil from whichthey are derived and are usually present as a 10 to 30 weight percentconcentration.

The monosulfonate fatty amido diamine salts of monocarboxylic acids ofthis invention are effective in liquid petroleum hydrocarbons includinglight distillates, i.e., liquid hydrocarbons boiling up to and includinggas oils, and lubricating oils. As examples they can be employed ingasoline, kerosene, petroleum solvents, diesel fuels, heating oils,neutral oils, etc. The amount employed in a given instance will. dependupon the character of the base oil and the degree of corrosioninhibition desired with a small but sufiicient amount being employed togive substantial corrosion inhibition. Generally, the inhibitor willcomprise from about 0.001 to 5.0 weight percent or more of the totalcomposition with larger amounts being used as the specific gravity orviscosity of the base oil increases. As examples, with gasoline theamount of inhibitor will vary generally from about 0.001 to 2 weightpercent of the total composition including the base oil with about 0.5to 2 percent being particularly useful for humidity cabinet protection.On the same basis, about 0.001 to 3 weight percent of inhibitor wouldnormally be used in diesel fuel with about 0.75 to 3 percent beingpreferred for flushing compositions. The corrosion inhibitors of thepresent invention may be used alone or in combination with otheradditives such as anti-foam agents, detergent additives, pourdepressants, viscosity index improvers, etc., which improve thecomposition in one or more respects. Since the mineral oil is present inrelatively large and major amounts the optimum concentration of anycombination of additives will, of course, depend upon the particulartype of mineral oil base stock and the potency of the additivecombination contained therein.

The following specific examples will serve to illustrate the presentinvention but they are not to be considered limiting.

EXAMPLE I Acorrosion inhibitor the following manner:

Six parts by weight of oleic acid, 10.5 parts by weight of Diamine 257,and 83.5 parts by weight of mahogany sulfonic acids percent solution inits base petroleum oil; 300 SUS at 100 F., Acid No. 16.4) were reactedat a temperature of 100 to 120 F. A clear homogeneous solution resultedwhich was a 25 percent concentrate of the monosulfonate fatty amidodiamine salt of the oleic acid. The solution had the followingproperties:

of this invention was prepared in EXAMPLE II A mono-sulfonate fattydiamine salt of oleic acid was prepared in the above manner by reacting15.5 parts by weight of the mono-oleate salt of a fatty diamine with84.5 parts by weight of mahogany sulfonic acids (10 percent solution inits base petroleum oil; 300 SUS at 100 F., Acid No. 16.4). The fattydiamine employed was of the formula RNH(CH NH in which R is the straightchain hydrocarbon radical of 16 to 18 carbon atoms, saturated andunsaturated, derived from tallow fatty acids. The product was a 24percent concentrate which analyzed as follows:

Gravity, API 23.7

Viscosity, SUS at 100 F. 451 Viscosity, SUS at 210 F. 60.5 Flash, F 350Fire, F. 410 Pour, F. -35 Color, NPA 7 Acid number 26.5 Saponificationnumber 26.4 Nitrogen, percent 0.69 Sulfur, percent 0.81

In order to show the outstanding corrosion characteristics of thecompounds of this invention, the novel inhibitor as prepared in ExampleI was blended with diesel fuel and subjected to a humidity cabinetcorrosion test identified as the MIL- 21260 type specification(Lubricating Oil, Internal Combustion Engine, Preservative). This testis carried out as follows:

Small sand blasted mild steel panels are dipped in the petroleumhydrocarbon and after draining two hours at room temperature aresuspended in a highly humid atmosphere, generally about 100 percenthumidity, at 120 F. in a special cabinet. The time of initial corrosionof the panels is noted. The humidity cabinet is provided with heatingunits and thermal regulators for automatic temperature control. tainedin the bottom of the cabinet and 8 linear feet per hour of clean air isbubbled through the water to assure high humidity at all times. Thesteel panels are suspended by stainless steel hooks around the peripheryof the humidity cabinet. About three complete changes of air per hourare provided in the cabinet. In order to pass the test, no more than 3rust spots 1 mm. in diameter should be observed on the panel after 6days exposure in the cabinet.

A water level of 8 inches is main- 6 A summary of the humidity cabinetresults obtained when using the mono-sulfonate fatty amido diamine saltsof monocarboxylic acids as a corrosion inhibitor in diesel fuel is shownbelow. The diesel fuel employed has an API gravity of 38.6, a boilingrange of 370 to 640 F. and an SUS viscosity of 35.6 at F. Theeffectiveness of the novel inhibitor as prepared in Example I isrevealed by the number of days the panel is exposed before failureoccurred, and as compared to the mono-sulfonatemono-oleate fatty diamineof Example II, striking differences in results were obtained. At thesame concentration of 0.69 percent the reaction product of Example Igave good protection for over nineteen days whereas the fatty diaminesalt of Example II was substantially less effective.

Table I MIL-L-2l260 HUMIDITY CABINET TEST RESULTS 1 Number of daysbefore 2 or 3 rust spots 1 mm. in diameter appear on test panel.

The following data of Table II illustrate the results obtained when thecompounds prepared in accordance with the present invention were testedin mineral oil products such as gasoline and diesel fuel for dynamiccorrosion inhibition properties. The reaction product of Ex ample II,which does not contain the amide linkage, is used for comparisonpurposes with the composition of the present invention (Example I) whichemploys a fatty amido diamine as the amine constituent. The DynamicCorrosion Test is a modification of ASTM test D-665-47T forrust-preventing characteristics of steam turbine oil in the presence ofwater and is useful for determining the protection afforded by corrosioninhibitors under dynamic conditions, e.g. as in pipelines. In thismodified procedure, a freshly ground rust test coupon consisting of/z-inch diameter by 5 /2 inches long mild steel rod is suspended in a400 ml. beaker equipped with a stirrer and placed in a temperaturecontrolled bath capable of maintaining the temperature of 100 1 F. Thetest fuel (350 ml.) is added and stirred for thirty minutes to allow therust inhibitor to precoat the test specimen. Part (50 m1.) of the testfuel is then removed and 30 cc. of distilled water is added. The mixtureis stirred for a fourhour test period. At the end of this period, thecoupon is removed, dried with suitable solvents, rated according to thefollowing scale:

A, no rust B trace rust surface area) (covering a maximum of 0.25% oftotal of surface area covered by rust B, 5 to 25% of surface areacovered by rust C, 25 to 50% of surface area covered by rust D, 50 to75% of surface area covered by rust E, 75 to 100% of surface areacovered by rust The test conditions are substantially more severe thanordinary conditions encountered so the results give a clear indicationof the effectiveness and amount of the novel corrosion inhibitorsrequired in the particular oil tested to obtain a rating of B++ orbetter.

aoaaaes 1 Pounds of inhibitor needed per 1000 barrels of hydrocarbon toobtain :11} rating or better in the modified ASTM-DSG Test (dry soapLiII gravity of 62.6; Reid Vapor Pressure 9.0; boiling range 0106 to 405F.: AS'IM Guru 2.7.

3 See Table I.

The reaction products of Examples I and II were added to diesel fuel andevaluated in accordance with the following static test procedure. A flatstrip of mild carbon steel (MW x /2 x 5%) is cleaned with naphtha orother solvent to remove grease and oil and then polished with emerycloth until no rust or pits remain. During and after these polishingoperations the strip should be handled with a clean lintless cloth or apiece of facial tissue. After the strip has been thus prepared it shouldbe carefully wiped free of emery dust. The specimen together with 100ml. of the sample to be tested are placed in a corked 4-ounce oil samplebottle which is allowed to lay on its side at room temperature for 1hour. The liquid should cover the test specimen during this contactperiod. Then add ml. of distilled water, cork tightly, and shakevigorously for 2 minutes to insure water wetting over the entire stripsurface. The specimen should be tightly wedged between the cork and thebottom of the bottle to minimize breakage. The bottle is then restoredto an upright'position and allowed to stand at room temperature. Thespecimen is examined for rust daily after each day the bottle is shakento replace water droplets on the specimen in the hydrocarbon phase thatmay have been disturbed during inspection. When 25 percent of thespecimen exposed in the aqueous phase becomes rusted the test hasfailed. The tests are run in quadruplicate and the average failure timeis reported.

As shown belowin Table III, the inhibitor compound of Example 1 gaveexcellent corrosion protection as indicated by the passing of 642 hoursbefore 25 percent of test coupon had rusted. The significance of thestatic test shows the usefulness of the inhibitor in systems where thehydrocarbon stock does not flow past the metal surface to replenish thecorrosion inhibitor, e.g. as in a storage tank. The diesel fuel employedhad an API gravity of 38.6, a boiling range of 370 to 640 F. and an SUSviscosity of 35.6 at 100 F.

Table III Static Test Results As pre- Inlubltor pared in ExampleInhibitor Hours 1 None 1. 5 lvlono oleate mono-sulfonate salt I 9 642 offatty amido diamine. Mono-oleate mono-sulfonate salt II 9 102 of fattydiamine.

1 Pounds per thousand barrels (dry soap basis).

1 Hours before 25 percent of the area of coupon exposed to the a ueousphase has rusted.

As previously indicated; the corrosion inhibitors of this invention canbe prepared by using more than the stoichiometric amount of thereactants and the excess can be included with the principal corrosioninhibitor. The following Example III illustrates the preparation of acorrosion inhibitor when using an excess of fatty amido diaminemono-oleate. Example IV is substantially the same preparation with theexception that a fatty diamine monooleate is employed rather than thefatty amido diamine mono-oleate. p

EXAMPLE III Twenty-five parts-by weight of the monooleate salt of thefatty amido diamine of Example I and parts by weight of oil-solublesulfonic acid (as a 10 percent concentration in its mineral base oil;300 SUS at F., Acid Number 16.4) were reacted at a temperature of 100 toF. A clear homogeneous solution resulted which was a 32.5 percentconcentration of the mono-sulfonate fatty amido diamine salt of theoleic acid together with the excess fatty amido diamine mono-oleate.

. E MPL IV A mono-sulfonate fatty diamine saltof olcic acid was preparedin the above manner by'reacting 25parts by weight of the mono-oleatesalt of the fatty diamine described in Example II with 75 parts byweight of mahogany sulfonic acids (10 percent concentration in its basepetroleum oil, 300 SUS at 100 F., Acid Number 16.4). The

reaction was carried out at a temperature of 100 to 120 F. and ahomogeneous solution resulted which was a 32.5 percent concentration ofthe monosulfonate fatty diamine salt of oleic acid together with excessfatty diamine monooleate.

The data of Table IVbelow illustrate the effectiveness of the fattyamido diamine mono-oleate mono-sulfonate inhibitors containing excessfatty amido diamine monooleate as a humidity cabinet corrosion inhibitoras compared to a fatty diamine mono-oleate mono-sulfonate which containsexcess fatty diamine mono-oleate. In Examples III and IV; the reactantsused to prepare the inhibitors shown in Table IV are in ratios of onemole of fatty diamine mono-oleate or fatty amido diamine monooleate to0.55 mole of sulfonic acid. The base oil employed was a diesel fuelwhich had an API gravity of 38.6, a boiling point of 370 to 640 F. andan SUS viscosity of 35.6 at 100 F. j

Table IV NULL-21200 HUMIDITY CABINET TEST RESULTS Ooncen- AveragePreparatration, number Corrosion inhibitor tion, weight of days Examplepercent, before dry soap rusting basis Fatty amido diamine mono-oleateIII .205 4 mono-sulfonate. Fattyamidodiaminemono-oleate III .65 14mono-sulfonate. Fatty amido diamine mono-cleats III .97 21+mono-sulfonate. LIOIlO OlBflfBIB-HY diamine mono- IV 295 1. 5

sulfonate Mnno-oleate fatty diamine mono- IV .65 4

sulfonete. Mono-oleate fatty diamine mono- 97 13 sulfonatc.

We claim: 1. A chemical compound selected from the formulae:

i R-G-NHR -l\|l R41\[l-O- -11:

R1-CO H 0 and 0 H H H O H RCNHR:-N-- I-? 1 0 H II Rr-fi-O in which R andR represent monovalent hydrocarbon 3. The compound of claim 2 wherein Ris the hydrocarbon radical of oleic acid; R is the aromatic hydrocarbonradical present in mahogany sulfonic acid and R and R each contain 3carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS2,583,772 Gunderson Jan. 29, 1952 10 2,596,925 Gunderson May 13, 19522,598,213 Blair May 27, 1952

1. A CHEMICAL COMPOUND SELECTED FROM THE FORMULAE: